In recent years, the University of North Texas Health Science Center in Fort Worth has experienced unprecedented growth in terms of programs and influx of grant funds. The development of core facilities supporting funded projects has somewhat lagged behind. In this shared instrument grant application, it is demonstrated that NIH funded projects on campus and at other universities in the Fort Worth/Arlington area can benefit significantly from the availability of a versatile 137Cs gamma irradiator. The capability to introduce with technical ease well-defined cellular damage is going to be exploited in a variety of projects and a variety of experimental systems. Certain projects are directly involved in studying DNA damage responses while others use this type of ionizing radiation merely as a tool, e.g. in order to introduce mutations. For instance, gamma irradiation in individual projects is used: 1) to induce cell cycle checkpoints and transcriptional changes in budding yeast. 2) to permit bone marrow manipulations for immunological studies. 3) as an apoptosis triggering agents in studies of protein kinase C. 4) to introduce oxidative stress in studies of cancer-relevant detoxification systems and in studies concerned with aging and Alzheimer's disease. 5) as a convenient and widely-accepted way to introduce mutations in C. elegans. Several secondary users have also been identified and it is hoped that access to this novel and important resource will not only lead to more successful grant applications but also to a widening of scope of research endeavors on campus. The resource is not characterized by high operating costs or difficult operational logistics. This instrument is mechanically simple, robust and maintenance-free. Irradiation times are brief and a large group of potential users can easily be accommodated. The individual projects of all primary users are funded by NIH grants, and their relevance for human health can easily be confirmed. In general, the study of effects of ionizing radiation is of tremendous medical importance because of its frequent use as a diagnostic and therapeutic agent. [unreadable] [unreadable] [unreadable]